1. Field of the Invention
The present invention generally relates to a frame structure for a vehicle and, more particularly, to a frame or chassis arrangement having a floor structure formed from a corrosion resistant, lightweight extrudable material.
2. Description of the Related Art
Japanese Unexamined Patent Publication (kokai) No. 11-272994 discloses an automotive frame structure wherein a floor member is extruded from a lightweight metallic material, such as an aluminum alloy, so as to have elongated closed hollow cross-sections extending in the fore-and-aft (longitudinal) direction of the vehicle body. In this conventional frame structure, however, the extruded floor member has a constant closed cross-sectional height and a constant wall thickness. As a result, the strength/rigidity of the floor member tends not to satisfy impact deformation requirements.
It is an object of the present invention to provide a frame/chassis structure for a vehicle, including an extruded floor structure or member, that supplies the required strength/rigidity for the automotive body floor.
These and other objects of the invention are met by an embodiment of the invention which provides an extruded floor member having at least partially closed cross-sectional extrusion features extending in a longitudinal direction. The floor member includes a plurality of sections comprising a tunnel section having a first cross-sectional configuration; a side sill section having a second cross-sectional configuration; and a flat section having a first portion and a second portion. The first portion and the second portion are separated by a high-strength third portion. The flat section is interposed between the tunnel section and the side sill section so that the first portion is located adjacent the tunnel section. The first portion, second portion and the third portion each respectively have third, fourth and fifth cross-sectional configurations. The longitudinal rigidity of the side sill section in the longitudinal direction is higher than the tunnel section and the flat section. The lateral rigidity of the second portion of the flat section is smaller than the lateral rigidity of the side sill section, and the lateral rigidity of the first portion of the flat section is substantially equal to the lateral rigidity of the second portion of the flat section.
Additional advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.